Estimating the measured OG

I tried searching but was unable to find my answer so sorry if a repost.

I'm new to brewing and just finished brewing my second batch, an all grain strawberry blonde ale.  It has been sitting in the primary for about 7 days now, and I realized I never got a measured OG when transferring from the boil kettle to my fermentor.  I got my measured pre-boil (1.037) pre boil volumes (7.75 gal) and finished boil volume (6.4 gal).  My estimated final OG should be 1.012 per brewsmith (recipe called for 1.011).

Is there a way to estimate what my measured OG should've been?  I was trying to finish up (late start on my brew day  ) and forgot to get a gravity reading prior to transfer.  This is purely from an efficiency standpoint as I'm trying to narrow down my efficiency for beersmith.

Any help is appreciated.
Cheers!

It's probably just a few points higher than your pre-boil gravity, but if the purpose of knowing this is to change efficiency values I'd suggest you hold off until you have a few more data points (brew sessions) and a trend starts to reveal itself.

"I got my measured pre-boil (1.037) pre boil volumes (7.75 gal) and finished boil volume (6.4 gal)."

Using this you can estimate the OG of your wort.  One thing that does not change during the boil (assuming that you are not adding in any sugars or fermentable items during the boil) is the amount of sugars the wort contains.  Boiling only concentrates the sugars.  You can do an estimate by tracking 'gravity points' before and after the boil.

So, your amount of sugars before the boil should equal the amount after the boil, thus:

Pre-boil volume * (pre-boil gravity - 1.000)*1000  = Post-boil volume * (post-boil gravity - 1.000) * 1000

In your case:  7.75 gal * (1.037 - 1.000) *1000 = 286.75 'gravity points' pre-boil

Since this should be the same as your post boil gravity points, you can get an estimate by reversing the calculation:

286.75 = post-boil volume [6.4 gal] * (post boil gravity - 1.000) * 1000. 

Post-boil gravity = 286.75 / 6.4 /1000 + 1.000 = 1.045

niiiicely done Oginme

Thank you Oginme!